The ionization devices known per se generally comprise sets of electrodes brought to a relatively high alternating or direct electric current (for example, comprised between 2 and 5 kV for installations of considerable flow of air). These electrodes are disposed along geometric grids in conduits or pipe-lines through-crossed by the gas or air to be ionised and are present in the form of points or wires borne by the walls of these conduits or pipe-lines. These ionization installations give relatively satisfactory results in industrial installations for the treatment of gas by ionization such as dust-removing installations by electrostatic precipitation but prove to be much less efficient in air conditioning installations by ionization.
These reduced-scale ionisation installations are, for example, designed to remove static electricity that appears on textile fibers during trituration or in sensitive electric equipment such as computors or integrated circuits, particularly during their production and their assembly. This lack of efficiency of medium-size ionisation installations seems to be due to the fact that, for reasons of costs and organisation of the air-conditioning installation, ionization electrodes are installed in an enclosure for the treatment of air and the treated air is distributed by relatively long conduits in utilisation zones such as the proximity of covers of textile threads charged with static electricity or, furthermore, assembly tables of printed circuits.
After positive or negative ionization of the air to be treated, the relatively turbulent passage of this ionised air in the distribution conduits provokes a "recombination" of the positive and negative ions, previously disassociated and the "recombination" or depolarization of the air considerably reduces the ionization rate of the treated air when it is delivered into the utilisation zone constituting a space to be air-conditioned by ionisation.